User interface for a portion of a display screen



The FIGURE is a front view of a user interface for a portion of a display screen showing the new design.

The broken line showing of various regions and the unshaded areas there within form no part of the claimed design. The broken line showing of the display screen is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 